The compound of formula (I) below, whose chemical name is 6β,7β;15β,16β-dimethylen-3-oxo-17α-pregn-4-ene-21,17-carbolactone, is commonly referred to as drospirenone:

Drospirenone is a synthetic steroid with progestogenic, antimineralocorticoid and antiandrogenic activity; by virtue of these properties it has long been used for preparing pharmaceutical compositions with contraceptive action for oral administration.
Various processes are known in the literature for preparing drospirenone.
The process described in European Patent EP 075189 B1 obtains the final product drospirenone through oxidation under heating of 17α-(3-hydroxypropyl)-6β, 7β,15β,16β-dimethylene-5β-androstane-3β,5,17β-triol with a mixture of pyridine/water/chromium(VI) oxide. This step represents a substantial drawback in the process: in fact, chromium(VI) oxide, like all Cr(VI) compounds, is an established carcinogen, the use of which is subject to such legislative restrictions that the precautions required during use and disposal of this product led to abandonment of the above industrial process.
A similar situation occurs with the process of U.S. Pat. No. 4,416,985, wherein drospirenone is obtained through oxidation under heating of 3β,5-dihydroxy-6β,7β;15β,16β-dimethylene-5β,17α-pregnane-21,17-carbolactone using a mixture of pyridine/water/chromium(VI) oxide.
Another process for preparing drospirenone is described in European Patent EP 918791 B8; in the process of this document drospirenone is obtained, still from 17α-(3-hydroxypropyl)-6β,7β,15β,16β-dimethylen-5β-androstan-3β,5,17β-triol, in two distinct steps and by using an oxidant such as e.g. potassium bromate in the presence of ruthenium salts as catalysts, which eventually must be completely removed from the product.
European patent EP 1828222 B1 discloses a further process, where the oxidation step is carried out using calcium hypochlorite as an oxidant in the presence, as catalyst, of the 2,2,6,6-tetramethylpiperidine-1-oxyl radical or a derivative thereof; in the process of this patent the oxidant is added in portions until completion of the reaction. This process overcomes the disadvantages of the prior art in that calcium hypochlorite is a non-carcinogenic reagent, nor is 2,2,6,6-tetramethylpiperidine-1-oxyl radical a metal catalyst requiring purification of the final product; however, the need for sequential reagent additions and analytical controls in the course of reaction, while being simple, hamper standardized production that should run continuously or nearly so. As a result, the method of this patent too has process drawbacks with regard to industrial production.
Thus, there is a continuing need for a simple process for drospirenone production which allows to overcome prior art limitations.
Hence, it is the purpose of the present invention to provide an industrial process which allows preparing drospirenone without using reagents that are either dangerous or whose use is restricted by industry regulations, and minimizing operator intervention during the process itself.